This invention relates generally to stock cutting means in metal producing plants and more particularly to a flying shear machine (or flying shears) for cutting hot-rolled steel strip in traveling state into sections of equal length or different lengths.
Flying shears heretofore installed in equipment for producing heavy gage plate from hot-rolled strip may be broadly divided into pendulum or rocker type shears and flying press type or so-called die-cut type shears. In pendulum or rocker type shears, opposed upper and lower shear blades both undergo reciprocating motion as they rotate about a center at the instant of swinging or rocking. For this reason, at the time of shearing, the angles of the upper and lower shear blades relative to the stock material vary continually with time.
In contrast, in a flying press type or so-called die-cut type shears, the opposed upper and lower shear blades undergo reciprocating movements in the vertical direction and the horizontal direction, and the angles of the upper and lower shear blades relative to the stock material do not vary, and, accordingly, perpendicularity of the plate cut surface is readily obtained. For this reason, flying press type shears are used almost exclusively in equipment for producing heavy gage plates such as those of 6 mm. or more, or 9 mm. or more in thickness.
This flying press type or so-called die-cut shear machine has a shiftable shear housing supported by a supporting device, examples of which are a device of a type which supports the shiftable shear housing on a slide surface or by means of wheels or cylindrical rollers, a device comprising a parallel link mechanism 1 as shown in FIG. 1, and a device which supports a shiftable shear housing 5 (as shown in FIG. 2 of the accompanying drawings briefly described hereinafter) by means of a mechanism approximating straight-line motion, called a Robert's mechanism, comprising a pair of links 3 and Tee-type link 4 connected to a housing 2.
In the supporting device which supports the shiftable shear housing on a sliding surface, however, it is difficult to obtain suitable lubrication of the slide surface, and, furthermore, as a consequence of biting in of scale and other abrasive material, the slide surface is readily damaged and subject to abnormal wear, seizure, and other impairment. In the supporting device employing wheels or cylindrical rollers, uneven wear due to offset contact and slippage relative to rails caused by off-center loading of the wheels or the cylindrical rollers readily arises.
In a parallel link mechanism 1 as illustrated in FIG. 1, pivoted connections 8 of a shear blade supporting beam 6 and pendulum arms 7 undergo arcuate motions, and a vertical movement of a degree which is more than necessary is imparted to the shear blade supporting beam 6. As a result, a vibrational load in the vertical direction due to the inertial mass of the shear blade supporting beam 6 acts on the frame 9, and noise is caused by the vertical vibration applied to the frame 9 and, in turn, to the shear machine base.
Furthermore, since the pendulum arms 7 swing through an angle of the order of 40.degree. at the most, it becomes difficult to form oil films for lubrication of the pivoted connections 8 in the case of high loads. In addition, since the shifting drive mechanism 10 for the reciprocating shear blade supporting beam functions also as a parallel crank mechanism 11, the period of velocity synchronization between the stock material and the shear blade supporting beams 6 and 12 at the time of shearing is short, being only instantaneous, problems arise in the flying shearing of heavy gage steel plates exceeding 6 or 9 mm. in thickness, which require relatively long velocity synchronization distances.
On this point, the shiftable shear housing supporting device shown in FIG. 2 is free of problems such as biting in of scale and other matter and uneven contact, and a movement approximating a straight-line movement is imparted to the shiftable shear housing 5, whereby the above described difficulties due to arcuate motion are eliminated. On the other hand, since a wide space is required for the installation of this device, the flying shear machine, disadvantageously, must be made large in bulk merely for the purpose of this installation in the case of a flying shear machine or relatively narrow machine width such as that used in equipment for producing heavy gage steel plate from hot-rolled strip.